Why?the Isodevice has not been found! Help a newer

[bynothing]

I USE The command ' sudo umount -l|isodevice'
but it return that the Isodevice has not been found!
why?
When i try to install , the system says that the Isodevice could not been umounted!

I am a completely new learner,I need you favour.thank you.It cannot input Chinese on my computer yet now!!

[ygf]

安装什么啊？系统还是应用程序？能给点详细的信息吗？

[ljweb]

应该是在硬盘模式安装系统了。